Electrodeposition of titanium



United States Patent ELECTRODEPOSITION OF TITANIUM Eugene Wainer,Cleveland Heights, Ohio, assignor, by mesne assignments, to HorizonsTitanium Corporation, Princeton, N. J., a corporation of New Jersey N0Drawing. Application October 8, 1952, Serial No. 313,795

Claims. (Cl. 204-64) This invention relates to the production ofmetallic titanium. More particularly, it relates to the production bythe electrolytic decomposition of titanium monoxide in a fused saltdiluent bath of titanium metal which can be recovered in a formsubstantially free from embrittling contaminants.

Pure titanium metal possesses many unique properties which are makingtitanium of increasing commercial importance. The valuable properties oftitanium may be impaired, however, if the metal is contaminated witheven small amounts of impurities such as oxygen, nitrogen or carbonwhich embrittle the metal to such an extent as to render it virtuallyimpossible to cold work. Considerable investigation has been directed tothe problem of developing a satisfactory process for the production oftitanium metal substantially free from these embrittling contaminants.Some of the processes which have been developed have resulted in theproduction of a satisfactory product but for economic or practicalreasons do not appear to be wholly satisfactory from a commercialstandoint.

p Among the most promising proposals for the production of titaniummetal are electrolytic processes in which titanium monoxide iselectrolyzed in fused salt baths. For example, the electrodecompositionof titanium monoxide in a fused salt bath composed of an alkali metalhalide has resulted in the production of a metallic titanium deposit onthe cathode. The metal produced, however, is in such finely dividedform, and the efficiency of the process so low, as to make this processcommercially unacceptable. It has also been proposed to electrolyzetitanium monoxide in a fused bath consisting of an alkaline earth halidewith or without the addition of an alkali metal halide. The titaniummetal deposited on the cathode in this process is exceptionally pure ifcertain conditions of operation are observed. For example, the optimumtemperature range within which the electrolysis must be carried out isfrom about 800 to 850 C. If the electrolysis is carried out much below800 C. the primary product at the cathode is metallic calcium, and ifthe temperature of the bath rises much above 850 C. the titanium metalis dispersed throughout the bath, thereby making it necessary to washthe entire bath in order to recover the titanium.

Furthermore, although exceptionally pure titanium metal is deposited onthe cathode within the optimum temperature range of the last mentionedprocess, it is obtained in such finely divided form that greatdifliculty is encountered in washing the metal particles free fromentrained salt without oxidizing the surface of the metal to anundesirable extent. Rather rigorous washing of the finely divided metalproduct with warm water and dilute acids is required to remove all theentrained salt there from. During the washing procedure the extremelysmall particles of titanium metal become coated with a film of oxidewhich, because of the high ratio of surface area to weight of theseparticles, contaminates and embrittles the titanium to such an extent asto render a metal ingot produced therefrom unworkable in the cold. Theproduction of a coarsely crystalline titanium metal by the electrolysisof titanium monoxide would be an important development in this art. Thelarger particles would be more readily washed free from entrained saltand would have a smaller surface area to weight ratio which, in turn,would tend to reduce the likelihood of excessive oxide contamination.

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I have made an important improvement in the process of producingtitanium metal by the electrolysis of titanium monoxide whereby suchcoarsely crystalline titanium can be readily produced. This improvementcomprises using as the fused salt diluent bath a mixture composed of atleast one alkali metal halide other than an alkali metal fluoride andfrom 2 to 30% by weight of at least one alkali metal fluotitanate. Thetitanium monoxide feed and the constituents of the bath preferablyshould be substantially anhydrous and of high purity. The metallicproduct of the electrolysis is substantially pure crystalline titaniummetal most of which has a particle size greater than that which willpass through a 200 mesh screen (Tyler standard) and among which aresingle crystals up to 0.5 inch in length. In my improved process theoxide component of the electrolytically decomposed titanium monoxidecombines with carbon from a carbonaceous anode with the concomitantevolution of carbon monoxide gas at the anode. The carbonaceous anode,therefore, is one of the reactants in my process. My invention may bepracticed within a relatively wide range of operating temperatures andpermits the fused salt diluent bath to be used indefinitely withoutbecoming dominated by decomposition products which would eventuallynecessitate discarding the bath.

The major constituent of the diluent bath of my invention is at leastone alkali metal halide other than the fluoride, preferably sodium orpotassium chloride, or mix tures of these two salts. It is importantthat the alkali metal chloride, bromide or iodide, or mixtures thereofwhich are used in the practice of my invention, be pure andsubstantially completely anhydrous. Both sodium and potassium chlorideare available in commercial quantities in a state of purity suflicientfor use in my process.

The alkali metal fluotitanate constituent of the bath may be eithersodium fluotitanate (NazTiFs) or potassium fluotitanate (KzTiFs), ormixtures thereof, potassium fluotitanate being preferred because of itsease of handling. Although fluotitanates of commercial grade may beused, I have found it advantageous to use a purified form of thesesalts. Moreover, I have found that the anhydrous form of thefluotitanate leads to further improved results. Fluotitanates of thepurity preferred for the practice of my invention may be readilyobtained by recrystallizing the salt once from water followed byfiltration and washing, and all moisture associated with the salt may beremoved by drying under vacuum of about 1 millimeter of mercury or lessat a temperature in the range of about to 200 C. The alkali metalfluotitanate may, if desired, be formed in the bath itself by placing ina molten bath of alkali metal halide a suitable amount of potassium orsodium fluoride and by then introducing anhydrous titanium tetrafluorideinto the bath, preferably in the vaporized form.

The diluent bath composed of the aforementioned alkali metal halide andalkali metal fluotitanate may be prepared either by mixing the pureanhydrous constituents together prior to fusion, or by introducing thecrystalline fluotitanate into an already fu'sed bath of the alkali metalhalide, or by forming the fluotitanate in a fused bath of the alkalimetal halide in the manner outlined hereinbefore. The bath shouldcontain from about 2 to 30% by weight of the alkali metal fluotitanate,and preferably from about 7 to 20% of the fluotitanate, the balance ofthe bath consisting of one or more of the aforementioned alkali metalhalides. Of course, the over-all composition of the bath changessomewhat upon the introduction of titanium monoxide and afterelectrolysis has commenced. However, under normal operating conditionsthe alkali metal fluotitanate and the alkali metal halide constituentsof the bath do not ap ear to be a reciabl affected by the electrolysisor t?) become iessivel; dominated by the products of decompositionthereof and therefore do not interfere with sustained continuous orincremental additions of the titaniferous source material to the bath.

The primary source of the titanium which is deposited on the cathodeduring the electrolysis is the titanium monoxide introduced into theaforementioned bath. Carbon monoxide, which is formed at thecarbonaceous anode, is removed from the bath as a gaseous eflluent.Consequently, the bath may be used continuously and apparentlyindefinitely with only the introduction of additional titanium monoxidethereinto to make up for the titanium metal deposited at the cathode.

The titanium monoxide (TiO) used n my process should be anhydrous andfree from any higher oxides of titanium. That is, it should have nosignificant content of such higher oxides as TizOs, Tisos or T102. Ifthe titanium monoxide is contaminated with higher oxides, theelectrolytic product at the cathode will be contaminated with an amountof oxygen approximately equivalent to the amount of higher oxidecontaminant in the titanium monoxide feed. Titanium monoxide of therequired purity may be obtained by the process described in thecopending patent applications of Messrs. Wainer, Steinberg and Topinka,S. N. 206,712, filed January 18, 1951, now U. S. Patent 2,681,847;Messrs. Wainer and Sibert, S. N. 202,805, filed December 26, 1950, andMessrs. Sibert and Carlton, S. N. 289,878, filed May 24, 1952, now U. S.Patent 2,681,849, and may be supplied directly to the diluent salt bathwithout intermediate treatment. I

The titanium monoxide is advantageously introduced into the molten bathas a finely divided powder added to the bath continuously orincrementally throughout the operation of the process, although it maybe effectively added in the form of relatively coarse granules whicndissolve relatively slowly in the bath so that only co nparativelyinfrequent additions of titanium monox de need be made. The rate atwhich the titanium monoxide dissolves in an unsaturated bath dependslargely upon the available surface area of the monoxide particles, andtherefore the rate of dissolution of the monoxide 1n the bath may becontrolled by the use of monoxide particles of predetermined size.

Both of the aforementioned procedures for the addition of titaniummonoxide to the diluent salt bath are suitable for maintaining thereinan effective amount of the monoxide for electrolysis. All amounts of themonoxide up to its limit of solubility in the bath are effective in thepractice of my invention, although higher concentrations within thisrange lead to higher outputs. However, if the titanium monoxide is addedas aforementioned in a manner which leaves some of the monoxideundissolved in the bath, care should be taken that the amount of anyfinely divided monoxide physically suspended in the bath does not exceedabout 3% by Weight of the bath for otherwise mechanical occlusion of themonoxide in the cathode deposit is encountered.

The electrodeposition of titanium monoxide may be carried out in thefused salt bath of my invention within a relatively wide range oftemperatures, voltages and current densities. The temperature of thediluent bath should be maintained within the range of about 550 and 950C. and preferably between about 600 and 800 C. In order to reach thelower temperatures of operation, eutectic mixtures of sodium andpotassium halides are generally required, the lowest temperature atwhich any specific diluent bath may be operated depending largely uponthe melting point and fluidity of the mixture of fused salts usedtherein. The maximum temperature at which the bath may be operateddepends upon the temperature at which the components of the bathcommence to decompose or volatilize and the tendency of carbon monoxideto combine with titanium metal at temperatures upwards of 850 C. to formtitanium carbide. The voltage at which the electrolysis is carried outmust be sufficient to electrolytically decompose the dissolved titaniummonoxide while at the same time the electrolytic decomposition of thealkali metal halide and alkali metal fluotitanate constituents of thediluent bath is minified. Due regard must also be paid to the physicaldimensions and internal resistance of the cell. With the type of cell Ihave employed in my process, and described further hereinafter, I havefound that a cell voltage in the range between about 3 and 7 volts issatisfactory to meet these requirements. The current density at thecathode does not appear to be critical within very wide limits. Thus, Ihave found that the current density may vary between about 10 and 500amperes per square decimeter. If the above temperature and currentdensity conditions are observed, crystalline titanium metal of highpurity is deposited on the cathode with the concomitant evolution ofcarbon monoxide at the anode without the formation of extraneousproducts of decomposition which g/ould tend to build up in and todominate the diluent ath.

As in other processes for the electrolytic production of titanium metalfrom a fused salt bath, precautions must be taken to avoid contaminationof the bath and of the titanium metal deposited on the cathode. Thus,the electrolysis should be carried out in a closed electrolytic cellunder an inert atmosphere. The inert atmosphere may be maintained andthe gaseous products of decomposition removed therefrom by sweeping theatmosphere in the cell with a purified inert gas such as argon orhelium, or the inert atmosphere may be provided by a vacuum, the vacuumbeing maintained and the gaseous products of decomposition being removedfrom the cell by active vacuum pumping throughout the process. Themetallic titanium deposited on the cathode must similarly be protectedfrom contact with air until it has been cooled well. below the bathtemperature, advantageously by maintaining it in an inert atmosphereuntil it has been cooled to approximately room temperature.

I have used a variety of electrolytic cells in carrying out my process.The cell may consist of a simple graphite container or crucible whichserves as the anode and a cathode of iron or similar metal disposedcentrally within the cell. The upper portion of the iron cathode isadvantageously provided with a graphite sleeve which sheathes thecathode at the salt line and in the region above the molten bath toprotect it from the corrosive effects of the gaseous products ofdecomposition of the bath. In such a simple electrolytic cell, carbonmonoxide is formed all over the inner surface of the anode including thebottom thereof. A portion of the carbon monoxide thus formed passes overthe surface of the metal on the cathode and, if the temperature of thebath is too high, there is some tendency for the hot carbon monoxide tocombine with the metallic titanium deposit to form titanium carbide.This tendency may be minimized, however, by maintaining the temperaturewithin the cell below about 800 C. throughout the electrolysis. Theefficiency of a simple electrolytic cell such as this is quite high, thecurrent efficiency being about 70 to and the metal recovery efficiencybeing in excess of Any tendency for titanium carbide to form at thecathode and for the deposited titanium metal to become contaminated withsuspended titanium monoxide may be overcome through the use of acompartmented cell, that is, a cell divided by an interior partitioninto anode and cathode compartments. The interior partition may be madeof graphite or other suitable material. The partition may be porous tofacilitate communication between the anode and cathode compartments, orsuch communication may be provided in the case of an imperforatepartition by submerging the partition in the liquid bath so that thereis a space of 1 or 2 inches above or below the partition for the flow ofliquid between the compartments. In such compartmented cellsa solidanode of graphite is used in the anode compartment and an iron cathodeis advantageously used in the cathode compartment. Titanium monoxidefeed is introduced into the anode compartment and is confined thereinuntil it dissolves in the fused salt bath. Carbon monoxide, resultingfrom consumption of the graphite anode, is evolved within the anodecompartment. Thus the titanium metal deposits on the cathode in a regionfree from both undissolved suspended titanium monoxide and evolvedcarbon monoxide gas. For continuous operation of the cell, the regionimmediately above the cathode should be provided with an air lockarrangement whereby the cathode with its deposit of titanium metal maybe removed and a new cathode inserted into thel cell without affectingthe inert atmosphere above the co Another advantageous form ofcompartmented cell comprises a graphite crucible which serves as theanode and which has an inner false wall within the crucible spaced aboutone-half inch therefrom. The false wall may advantageously be made ofthin graphite bored full of minute holes. To avoid having carbonmonoxide form on and evolve from the bottom of the crucible within thecircular false wall, the bottom may be covered with a sintered block oftitanium monoxide. Because the elec' trical conductivity of titaniummonoxide is appreciably less than that of graphite, the majority of thecell current passes into the fused salt bath from the wall of thecrucible without affecting the sintered block of titanium monoxide whichcovers the bottom thereof. Titanium monoxide feed is introduced into thefused bath in the annular space between the wall of the crucible and theinterior false wall. The cathode, which may advantageously be an ironrod, is located in the bath centrally within the false wall and thus ina region free from undissolved suspended titanium monoxide and evolvedcarbon monoxide gas.

Still another form of cell which I have found to operate satisfactorilyhas disposed therein a hollow graphite anode of thick wall section madeporous by drilling a number of small holes in it. The cathode is locatedwithin the cell an appreciable distance from the anode but is notseparated therefrom by an interior partition or false wall. Titaniummonoxide is fed into the interior of the hollow anode where it isretained until it passes into solution. The carbon monoxide formedduring the electrolysis is vented from the cell directly in the area ofthe anode.

The following examples are illustrative but not limitative of myinvention:

Example I A furnace was provided in which the electrolysis could becarried out in an inert atmosphere. The furnace was equipped with an airlock arrangement to permit access to the interior of the furnace withoutaffecting the inert atmosphere therein. A graphite crucible which servedas the anode of the electrolytic cell and also as the bath confiningpart thereof was placed within the furnace beneath the air lock. Thecathode was not placed in the cell at this stage of preparation forelectrolysis. The cathode comprised an iron rod encased at its upper endin a graphite tube which, when the bath was in operation, served toshield the iron rod from any gaseous products of decomposition of thebath. An inert atmosphere was established within the furnace by passingthrough the furnace argon gas substantially free of nitrogen, oxygen andwater vapor. The furnace was heated to 800 C. and then 200 parts (asused in this and the succeeding examples, parts refers to parts byweight of the diluent bath) of chemically pure sodium chloride wereadded to the graphite crucible. The heating was continued until thesodium chloride became molten after which 200 parts of potassiumfluotitanate were added thereto. The potassium fiuotitanate had beenpurified by recrystallizing the salt once from water and thereaftervacuum-drying the salt at 180 C.

After the molten diluent bath was prepared 5 parts of titanium monoxidewere added thereto. The substantially completely pure and anhydroustitanium monoxide was in the form of minus 325 mesh (Tyler standard)particles. About five minutes thereafter, the iron cathode was insertedinto the bath so that the bath completely covered the bare iron rod atthe lower end thereof and electrolysis was thereupon initiated.

The electrolysis was carried out at 750 C. and at a current density of350 amperes per square decimeter. The initial voltage was approximately4.2 volts. However, as the electrolysis continued, the voltage rosegradually to about 5.1 volts at which it leveled off after about onehour of operation. During the initial stage of operation a noticeableodor of chlorine developed. After the first five or ten minutes,however, the odor of chlorine died down rapidly. Throughout theelectrolysis pure titanium monoxide was added to the bath in incrementsof 5 parts every 3 minutes and carbon monoxide evolved from the bath andwas removed from the furnace by sweeping the furnace atmosphere withpurified argon gas. After about an hour of operation the electrolysisand the addition of titanium monoxide were stopped and the cathode wasraised above the surface of the bath. The molten salt was allowed todrain from the cathode and then the cathode was raised into the chamberof the air lock where it was allowed to cool to room temperature.

Upon the removal of the first cathode a second cath ode was insertedinto the bath as before. The electrolysis was recommenced and 5 parts ofminus 325 mesh titanium monoxide were again added to the bath every 3minutes. The bath was maintained at 750 C. and the voltage leveled offat approximately 5 volts almost at once. Electrolysis was againcontinued for about an hour and was then stopped. The second cathode wasremoved, drained of fused salt and allowed to cool in an inertatmosphere and a fresh cathode was inserted into the bath as before.Thereafter the electrolysis was continued under substantially the sameconditions with the fresh third cathode and so forth for a number ofsuccessive runs.

After washing and drying the product of the first cathode a yield of 60parts of pure titanium metal was obtained. About 65% of the metalproduct was in the form of plus 200 mesh particles and a portion of theplus 200 mesh material was in the form of granules considerably coarserthan 10 mesh. The recovery of titanium metal on the first cathode wasapproximately 50% on a metal basis of the titanium introduced into thebath during the first period of operation and was produced at a currentefficiency of about 45%. A yield of 75 parts of titanium metal wasobtained after washing and drying the product on the second cathode.This was equivalent to a metal recovery efficiency of over 60% of thetitanium introduced into the bath during the second period of operationand represented a current efiiciency of over 60%. About 110 parts oftitanium metal were recovered from the third cathode, a yield equivalentto a metal recovery etficiency of at a current efficiency of 91%.Substantially all of this metal was coarser than 20 mesh and over halfof the product was in the form of single crystals approximately 0.2 inchin length. Metal recovery efiiciencies on oathodes used subsequent tothe third cathode varied between 80 and 100% at current efficiencies ofthe order of 70 to The coarseness of the metal product remained atsubstantially the same level as that reported for the third cathode andthe bath was quiet in operation with consistently uniform results.

Example II The electrolytic cell and the mode of operation weresubstantially the same as reported in Example I. The diluent bathconsisted of 2000 parts of potassium chloride and 200 parts of potassiumfiuotitanate. The electrolysis was carried out at 780 C., while voltageand amperage conditions were approximately the same as in Example I.

Pure titanium monoxide having a particle size of minus 325 mesh wasadded to the bath at the rate of 3 parts every 5 minutes. Fresh cathodeswere placed in the bath about every hour. The yield of titanium metal,current efficiency and particle size of titanium metal product wereapproximately the same as those reported in Example I.

Example III The electrolytic cell and mode of operation were the same asset forth in Example I. The diluent bath consisted of 1000 parts ofsodium chloride, 1000 parts potassium chloride and 200 parts ofpotassium fiuotitanate. The electrolysis was carried out at 650 C. andthe cell voltage varied between 3 and 5 volts. In all other respects theconditions of operation were substantially the same as described inExample I. The metal recovery efiicrency, current eificiency, andparticle size of the titanium metal product were all substantially thesame as those obtained at corresponding stages in Example I.

Example IV The electrolytic cell and the mode of operation were the sameas set forth in Example I. The bath consisted of 2000 parts of sodiumchloride and 50 parts of potassium fiuotitanate. For the first twoone-hour periods of operation, during which titanium metal was depositedon the first and second cathodes, titanium monoxide was added at therate of about 2.5 parts every 3 minutes. Thereafter, for all cathodessubsequent to the first and second, the bath was operated under the samecharge conditions as set forth in Example I. In each operating periodsubsequent to the third period the metal recovery efficiencies weresubstantially the same as for the corresponding periods in theoperation'described in Example I.

Example V A compartmented electrolytic cell was used in place of thesimple electrolytic cell of the prior examples. The interior of the cellwas divided into anode and cathode compartments by a partition made ofgraphite which was submerged to a depth of two inches below the bathlevel. The anode was made of graphite and was centrally disposed withinthe anode compartment. The cathode was an iron rod encased at its upperend in a protective graphite sheath and was disposed centrally withinthe cathode compartment so that the level of the molten bath completelycovered the bare iron lower portion of the cathode. The cell was placedwithin the furnace so that the cathode could be removed therefrom and anew cathode inserted therein through the air lock of the furnace.

The bath composition was the same as that reported in Example I, thatis, 200 parts of sodium chloride and 200 parts of potassiumfluotitanate. About 300 parts of titanium monoxide, in the form of minus100 mesh particles, was initially added to the bath in the anodecompartment and no further additions of the monoxide were made duringthe operation of the cell. The bath in the anode compartment was stirredoccasionally to facilitate the dissolution of the titanium monoxidetherein.

The bath was maintained at approximately the same temperature, i. e.,750 C., as in Example I. The cell voltage ranged between 6 and 7 voltsand the current densities were substantially the same as those reportedin the previous examples. The metal recovery and current efliciencieswere approximately the same as those encountered in the correspondingoperation stages of the simple cell of Example I subsequent to the thirdperiod.

Example VI A heavy-walled graphite crucible was used which wasconcentrically divided by an inner false wall into an annular anodecompartment and a central cathode compartment. The bottom of the insideof the crucible was covered by a heavily sintered slab of titaniummonoxide about one-quarter inch thick. The inner false wall was spacedabout one-half inch from the wall of the crucible and was made of thingraphite pierced approximately every half inch with A inch holes. Therelatively heavy walls of the graphite crucible served as the anode ofthe cell and an iron cathode was disposed centrally Within the centralcathode compartment. The cell was placed within the furnace so that thecathode could be removed from and a new cathode introduced into the cellthrough the air lock of the furnace.

The composition of the bath was the same as reported for Example I. Arelatively large quantity of pure t1- tanium monoxide in the form ofminus 325 mesh particles was introduced into the annular space betweenthe graphite crucible and the porous graphite false wall and no furtheradditions thereof were made during the operation of the cell. The bathtemperature, voltage, and current density conditions and results weresubstantially the same as those reported in Example I.

Through the use of the fused salt diluent bath of my invention in theelectrolytic decomposition of titanium monoxide, I have found that 1 canobtain an exceptionally pure titanium metal in coarsely crystallineform. T1- tanium is deposited on the cathode in the form of singlecrystals which frequently weigh as much as one gram and measure up toone-half inch in length. These crystals of titanium are readily washedfree of entrained salt without excessive oxidation thereof so that aningot of titanium substantially free from embrittling contaminants maybe produced therefrom. Furthermore, under normal operating conditions,the fused salt diluent bath is not adversely affected by theelectrolysis of the titanium monoxide nor does the bath becomecontaminated with injurious byproducts of the electrolytic decompositionthereof. Moreover, the diluent bath of my invention makes possible theuse of a wide range of operating temperatures and current densitieswhich heretofore have been found impossible to attain.

I claim:

1. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath whichcomprises: preparing a fused electrolyte consisting essentially of atleast one alkali metal halide from the group consisting of alkali metalchlorides, alkali metal bromides and alkali metal iodides and between 2%and 30% by weight of at least one alkali metal fiuotitanate, introducingsubstantially pure titanium monoxide into the said fused electrolyte toform a fused salt cell bath, passing an electrolyzing current throughthe fused bath between an anode and a cathode in contact with said bath,and recovering the resultant cathodically deposited titanium.

2. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath whichcomprises: preparing a fused electrolyte consisting essentially of atleast one alkali metal halide from the group consisting of alkali metalchlorides, alkali metal bromides and alkali metal iodides and between 7%and 20% by weight of at least one alkali metal fluotitanate, introducingsubstantially pure titanium monoxide into the said fused electrolyte toform a fused salt cell bath, passing an electrolyzing current throughthe fused bath between an anode and a cathode in contact with said bath,and recovering the resultant cathodically deposited titanium.

3. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath whichcomprises: preparing a fused electrolyte consisting essentially of atleast one alkali metal halide from the group consisting of alkali metalchlorides, alkali metal bromides and alkali metal iodides and between 2%and 30% by weight of at least one alkali metal fluotitanate, introducingsubstantially pure titanium monoxide into the said fused electrolye toform a fused salt cell bath, maintaining the bath temperature between550 C. and 950 C. while passing an electrolyzing current through thefused bath between an anode and a cathode in contact with said bath, andrecovering the resultant cathodically deposited titanium.

4. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath whichcomprises: preparing a fused electrolyte consisting essentially of atleast one alkali metal halide from the group consisting of alkali metalchlorides, alkali metal bromides and alkali metal iodides and between 2%and 30% by weight of at least one alkali metal fiuotitanate,progressively introducing substantially pure titanium monoxide into thesaid fused electrolyte to form a fused salt cell bath, passing anclectrolyzing current through the fused bath between an anode and acathode in contact with said bath, the rate of introduction of thetitanium monoxide being substantially equivalent to the rate ofelectrolytic decomposition of the titanium monoxide and recovering theresultant cathodically deposited titanium.

5. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath whichcomprises: preparing a fused electrolyte consisting essentially of atleast one alkali metal halide from the group consisting of alkali metalchlorides, alkali metal bromides and alkali metal iodides and between 2%and 30% by weight of at least one alkali metal fiuotitanate, introducingsubstantially pure titanium monoxide into the said fused electrolyte inan amount greater than will dissolve in the said electrolyte and therebyforming a fused salt cell bath, passing an electrolyzing current throughthe fused bath between an anode and a cathode in contact with said bath,progressively dissolving the undissolved titanium monoxide in said fusedbath at a rate substantially equivalent to the rate of electrolyticdecomposition of the titanium monoxide, and recovering the resultantcathodically deposited titanium.

6. A process for electrodcpositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath whichcomprises: preparing a fused electrolyte consisting essentially of atleast one alkali metal halide from the group consisting of alkali metalchlorides, alkali metal bromides and alkali metal iodides and between 2%and 30% by weight of at least one alkali metal fiuotitanate, introducingsubstantially pure titanium monoxide into the said fused electrolyte toform a fused salt cell bath, passing an electrolyzing current throughthe fused bath between an anode and a cathode in contact with said bath,continuing the introduction of substantially pure titanium monoxide intothe fused bath at a rate which maintains the amount of undissolvedsuspended titanium monoxide in the bath below a concentration of about3% by weight of the bath and recovering the resultant cathodicallydeposited titanium.

7. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath whichcomprises: preparing a fused electrolyte consisting essentially of atleast one alkali metal halide from the group consisting of alkali metalchlorides, alkali metal bromides and alkali metal iodides and between 2%and 30% by weight of at least one alkali metal fluotitanate,progressively introducing substantially pure titanium monoxide into thesaid fused electrolyte to form a fused salt cell bath, progressivelydissolving said titanium monoxide in said bath at a rate Substantiallyequivalent to the rate of electrolytic decomposition of the titaniummonoxide while maintaining any undissolved suspended titanium monoxidein the bath below a concentration of about 3% by weight of the bath,passing an electrolyzing current through the fused bath between an anodeand a cathode in contact with said bath, and recovering the resultantcathodically deposited titanium.

8. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath whichcomprises: preparing a fused electrolyte consisting essentially of atleast one alkali metal halide from the group consisting of alkali metalchlorides, alkali metal bromides and alkali metal iodides and between 2%and 30% by weight of at least one alkali metal fluotitanate, introducingsubstantially pure titanium monoxide into the said fused electrolyte toform a fused salt cell bath, passing an electrolyzing current throughthe fused bath between a carbonaceous anode and a cathode in contactwith said bath, and recovering the resultant cathodically depositedtitanium.

9. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt bath in acompartmented cell which comprises: preparing a fused electrolyteconsisting essentially of at least one alkali metal halide from thegroup consisting of alkali metal chlorides, alkali metal bromides andalkali metal iodides and between 2% and 30% by weight of at least onealkali ducing substantially pure titanium monoxide into the metalfluotitanate, introfused electrolyte in the anode compartment of thecell to form a fused salt cell bath, passing an electrolyzing currentthrough the fused bath between an anode and a cathode in contact withsaid bath, and recovering the resultant cathodically deposited titanium.

10'. A process for electrodepositing titanium metal in the form of acoarse crystalline electrodeposit from a fused salt both whichcomprises: preparing a fused electrolyte consisting essentially ofbetween 98% and 70% by weight of at least one chloride from the groupconsisting of sodium chloride and mixtures of sodium chloride andpotassium chloride and between 2% and 30% by weight of at least onefluotitanate of the group consisting of sodium fluotitanate andpotassium fluotitanate, introducing substantially pure titanium monoxideinto the said fused electrolyte to form a fused salt cell bath, passingan electrolyzing current through the fused bath between an anode and acathode in contact with said bath, and recovering the resultantcathodically deposited titanium.

Metal Industry, June 29, 1945, page 406 of article by Powell. (Copy inSci. Lib.)

Journal of Applied Chemistry (U. S. S. R. 13 (1940), pages 51-65,article by Sklarenko et vol.

1. A PROCESS FOR ELECTRODEPOSITING TITANIUM METAL IN THE FORM OF ACOARSE CYSTALLINE ELECTRODEPOSIT FROM A FUSED SALT BATH WHICH COMPRISES:PREPARING A FUSED ELECTROLYTE CONSISTING ESSENTIALLY OF AT LEAST ONEALKALI METAL HALIDE FROM THE GROUP CONSISTING OF ALKALI METAL CHLORIDES,ALAKALI METAL BROMIDES AND ALKALI METAL IODIDES AND BETWEEN 2% AND 30%BY WEIGHT OF AT LEAST ONE ALKALI METAL FLUOTITANATE, INTRODUCINGSUBSTANTIALLY PURE TITANIUM MONOXIDE INTO THE SAID FUSED ELECTROLYTE TOFORM A FUSED SALT CELL BATH, PASSING AN ELECTROLYZING CURRENT THROUGHTHE FUSED BATH BETWEEN AN ANODE AND A CATHODE IN CONTACT WITH SAID BATH,AND RECOVERING THE RESULTANT CATHODICALLY DEPOSITED TITANIUM.